Improvement in electro-magnetic alarm-bells



M. G. FARMER. ELECTROMAGNETIC BELL Patented May 4, 1852.

UNITED STATES MOSES Gr. FARMER, OF SALEM, MASSACHUSETTS IMPROVEMENT IN, E LECTRO-MAGNETIC ALARM-BELLS.

Specification forming part of Letters Patent No. 8 920, dated May 4, 1852.

' To all whom it may concern:

Be it known that I, MOSES GERRISH FAR- MER, of Salem, in the county ofEsseX and State of Massachusetts, have invented a new and useful Improvement on Machines for Striking Bells by Electro-Magnetism 5 andI do hereby declare that the following is a full, clear, and exact description of the construction and operation of the same, reference being had to the annexed drawings, making a part of thisspecification, in which- Figure I is a perspective view of that part of themachine which constitutes my invention, termed in the subjoined description the liberating'apparatus. "Fig. II is a perspective view of the machine, showingthe position of the bell, the hammer, the-striking apparatus, and its connection with the liberating part of the machine. I

My invention consists of mechanism of peculiar construction, which is put in operation by electromagnetism, and so combined with a train of wheel-work, cams, spring, weights, and a hammer, as to cause successive blows to he struck upon a bell any required number of times, the main feature of the invention consisting in this, that I am enabled by its use to bring into action any desirable amount of force, either .of gravity, of a spring,-of currents of air, or of steam, and control the duration of the same by the eleclro-magnet.

In Figs. I'and II the frame of the machine is shown at II. An electro-magnet, L L, Fig. I, is placed in a horizontal position near to one end of the machine. I An upright .bar,.c, hav in g its center of motion upon the rocker-shaft J is attached to the armature K of the magnet. The top of the bar 0 is made sufificientl y broad to allow the end of the arm N to rest upon it at b, the opposite end of the arm N being firmly affixed to the rocker-shaft O O, which is supported by the upright stands 0 C. To the same shaft 0 0 there are also afiixed three arms or levers, A, P, andf. A is an arm which may be about ten inches in length, having a weight, a, at its upper end. This ballor weight is not vertical with the rocker-shaft O, to which it is attached, but is inclined at such anangle asto insure its fall whenever the horizontal bar N is not supported by the upright bar 0. The distance through which the bar a is al lowed to fall is regulated by the rest W. The

arm B may be two or three inches in length, and is afiixed to the rocker-shaft O in'such a position as to actupon the end of the horizontal latch-shaped detent d and raise it from the pin or stud e. The detent d is supported at one end by a stud, V, upon which it turns. The opposite end carries a pin, Q, which falls'upon another pin or stop, H, attached. to the stand 0, and prevents the dete'nt d from falling 'lower than is necessary. The arm f, also firmly fastened to the rocker-shaft O, has at its lower end a stud or pin, D, placed in such a position as to come in contact with the cam g g, as hereinafter described.

The horizontal shaft E E,which is supported in the stands F F, placed upon opposite sides of the frame I I, carries the dog S, the pinion G, the gear T, and the cam or wiper 9, all of which are firmly secured to the shaft by splines or other suitable device. The cam g may be of about the same form shown in the drawings, its shape being such as to insure (by the intervention of the stud D, the bar f, and therockershaft 0) the elevation of the arm and ball A a to the required height, and at the same time allow it to fallupon the rest W.

The pinion U, placed below the gear 1 and driven by it, gives motion, by means of the horizontal shaft r, to the vanc or fan hh,which may be placed outside of the frame I. The bar i '5, to the opposite ends of which the vanes hh are fastend, turns freely upon the shaft 1. It carries a pawl, Y, and spring X, so placed that the pawl may play in the ratchet Z,which is firmly fixed to the shaft.

The pinion G forms a connection between the mechanism above described and the common strikingapparatusot'a tower-clock, Upon the latter machine I claim no improvements, as my invention relates exclusively tothe liberating apparatus, as hereinbcfore stated.

In Fig. II, which shows the general construction and relative position of the principal parts of the machine, TB represents a section of the lip of a bell; II, the hammer; M, the weight; n, the crank, by turning whichthe weight is wound up.

The pinion G, Fig. I, plays in the gear T, Fig. II, by which a connection is established between the striking part of the mechanism and the liberating apparatus.

The action of the weight M causes the shaft mer upon the bell at each of its revolutions.

To set the mechanism herein described in motion a current of electricity, generated by a suitable battery, is'passed through the coils of the magnets L L, the armature K is at tracted to the magnet, the upright arm 0 moves with it, the horizontal arm N is nolonger supported, and the weighted arm A falls over until stopped by the adjustable rest W in front of it. In falling the lever Praises the latch-- shaped detent d. The dog S, carryingthe pin 6 attached to the same axis with the cam g, and connected with the train of wheels of the striking machinery, is thusliberated and begins to revolve. In so doingthe cam grev'olves and swings forward the bar f attached to the axis of the falling arm A, which is thus raised to. its original position. The horizontal lever N catches again at b if the armature has been released, the detent dfalls and comes in contact with the pin 0, thus arresting the dog Sat the end of one revolution. This occupies one or two seconds, and in the meantime the weight M has fallen a short distance and a single blow has been struck by the hammer upon the bell. If the armature K were not released from the attraction of the electro-magnet the horizontal lever N would not catch at b, and the machine would continue to strike until the circuit-influencing ,eleetro-magnet was interrupted.

The red lines in the drawings show the position of a spring, 4, of india-rubber or other elastic material, one end being attached at 5 to the-falling arm A, and the other end fastened to the frame of the machine, asat 6. As the arm rises the spring is extended. As it falls its velocity is increased by the contraction of the spring.

It is obvious that either the weight a or the spring 4 may be used separately, or their action may be combined, as above described.

I claim as my invention;-

The combination, substantially as herein set forth, of the electro-magnetand armature, or itselectro-ma-gnetic equivalent, with the talling ball or spring and the detents, and the lifting-cam onits equivalents, so arranged that when the ball is supported by the armature a slight force only of the electro-magnetis re- ,quired to trip the ball, which ball infalling requires sufficient momentum to produce much greater mechanical effects than the magnet alone, the velocity of the ball in falling being still furtheraccelerated by the force of a spring, if desired. Thepower thus obtained 1 use in the manner and for the purpose herein. described.

' MOSES G. FARMER. [L; s.]

In presence of- FRANCIS L. BATCHELDER,

SAML. BATCHELDER, Jr. 

